The Computer History Museum

The museum, in Mountain View, California, is a short 10 minute drive from us. We’ve lived in the Bay Area for 6 years and hadn’t been yet, so we decided it was time.

It was a great way to spend a day. The main exhibit walks you through the evolution of computers: abacuses, slide rules, many other mechanical basic math machines, punch cards, early vacuum tube computers, early transistor-based computers, memory, storage, mainframes, personal computers, video games. With examples on display of all of these.

A demonstration of a modern construction of Charles Babbage‘s Difference Engine No. 2. This thing is amazing. The operator winds a crank and the machine calculates 7th degree polynomials purely mechanically. Gears and springs and sprockets, oh my. There are videos on YouTube.

A demonstration of the only working PDP-1 by Steve Russell and Peter Samson. The two met at MIT 50 years ago, where they wrote code for a PDP-1. Specifically, Steve Russell created Spacewar! and Peter Samson wrote a music program, among other things.

We stood by as they loaded programs from paper tape onto the machine and ran them. They ran Peter’s music program first. Interesting story: They had paper tape copies of the music data Peter encoded in the 1960s, but the music playing program had been lost. As part of the PDP-1 restoration effort, sometime in the last few years Peter reverse engineered the data format of the music and rewrote his music playing program. We got to hear Bach’s Organ Concerto No. 1 in G Major, 3rd movement, BWV 592. It sounded amazing.

Next up was Spacewar! The museum has connected arcade buttons to the PDP-1 for controlling the two ships. Emily and I actually played the original Spacewar! game on a real live PDP-1 while standing next to the guy who wrote it—crazy!